| 6 | describes.fakeWin('DOM - layout - intersection observer', {}, (env) => { |
| 7 | function getInObConstructorStub() { |
| 8 | const ctor = (cb) => { |
| 9 | if (ctor.callback) { |
| 10 | throw new Error('Only a single InOb instance allowed per Window.'); |
| 11 | } |
| 12 | const observedEls = new Set(); |
| 13 | ctor.callback = (entries) => { |
| 14 | if (entries.some((x) => !observedEls.has(x.target))) { |
| 15 | throw new Error( |
| 16 | 'Attempted to fire intersection for unobserved element.' |
| 17 | ); |
| 18 | } |
| 19 | cb(entries); |
| 20 | }; |
| 21 | return { |
| 22 | observe: (e) => observedEls.add(e), |
| 23 | unobserve: (e) => observedEls.delete(e), |
| 24 | disconnect: () => observedEls.clear(), |
| 25 | }; |
| 26 | }; |
| 27 | return ctor; |
| 28 | } |
| 29 | |